基于模式转换的镀膜长周期光纤光栅传感器的结构优化设计  

Design Optimization of Coated Long-Period Fiber Grating Based on Mode Transition

作　　者：顾铮■ 蓝锦龙[1] 

机构地区：[1]上海理工大学理学院光电功能薄膜实验室,上海200093

出　　处：《中国激光》2014年第1期133-138,共6页Chinese Journal of Lasers

基　　金：国家自然科学基金(60777035);教育部科学技术研究重点项目(208040);上海市教育委员会科研创新重点项目(11ZZ131);上海市重点学科建设项目(S30502)

摘　　要：基于耦合模理论,根据镀膜长周期光纤光栅(LPFG)包层模有效折射率随膜层参数的变化,指出了模式转换区的划分及特点,考察了模式转换区及其附近LPFG透射谱折射率的响应特性。从传感器设计角度,进一步针对波长偏移和透射率两种检测类型,给出了两类灵敏度的定义,讨论了模式转换区及其附近灵敏度随薄膜参数与光栅参数变化的关系,通过优化设计,给出了高灵敏度对应的最佳设计参数带及区域。结果表明,选择合适的膜层参数与光栅参数,利用波长偏移和透射率两种检测方法,该传感器对薄膜折射率的分辨率均可达10-7以上,且模式转换区适合于制作波长偏移型的传感器,模式转换区附近则适合用于制作透射率型传感器。Based on the coupled-mode theory, according to the variation of effective index of cladding modes in coated long-period fiber grating （LPFG） with the film parameters, the partition and characteristics of mode transition region are pointed out. The response characteristics of refractive index in coated LPFG transmission spectrum in mode transition region and its vicinity are investigated. Further, the two kinds of sensitivity definitions are given for the different detection types of wavelength shift and amplitude change from the aspect of sensor design. The changes of sensitivity with film parameters and grating parameters are discussed. By using optimization method, the optimum design parameters and regions with high sensitivity are obtained. The results show that the sensor resolution of film refractive index can be also available to 10-7 , if detected by wavelength shift and transmittance change. When the suitable film parameters and grating parameters are selected, mode transition region is fit for the sensor detected by wavelength shift, while the vicinity of mode transition region is fit for the sensor detected by transmittance.

关 键 词：光纤光学 镀膜长周期光纤光栅 模式转换 灵敏度 

分 类 号：TN253[电子电信—物理电子学]